Two-filament incandescent lamp



. 'R. N. FALGE TWQ-FILAMENT INCANDESCENT LAMP July 23, '1 929.

Filed Aug. 17, 1921 Fig. 1.

- INS/EN TUB RUBERT AZ. $142553 lamp to be Patented July 23, 1929.

UNITED} stare Pica.

ROBERT N. FALGE, OF CLEVELAND, OHIO, ASSIGNOR- T0 GENERAL ELECTRIC COMPANY,

A QORPORATION OF NEW YORK.

TWO-FILAMEN T INC ANDESCFNT LAMP.

. lamps and more particularly with such lamps used for projection purposes, as, for instance, in automobile headlights. These lamps'usually contain a major filament of high candlepower and aminor filament of comparatively 10 low candle-power and the filaments are coiled and located close together in order to obtain the proper light distribution. In the application of R. F. Strickland of even date herewith, is disclosed an arrangement of the major and minor filaments which permits an accurate and efficient manufacture and which will retain its construction and relative arrangement of parts under the extreme conditions of temperature which aris during the operation of such lamps andof vibration in automobile service. My invention, in one aspect thereof, is an improvement upon the arrangement disclosed in that application.

.My invention consists of a substantially uni-directional filament preferably, coiled which is mounted preferably with its geometric center substantially coinciding with the geometric center of a second filament which at least partially surrounds the same and isdisposed in a plane transverse to the plane of the latter which makes an oblique angle with the-line of intersection of the two planes. The plane of the second filament preferably includes the axis of the lamp or is parallelthereto. The coincidence of the geometric" centers is preferred as it facilitates the mak mg of a quite accurate adjustment, With the usual mounting equipment, of the position of I the lamp with reference to the focus of the parabolic reflector which is ordinarily'used, as set forth in the Strickland application.

I The disposition of the substantially'uni directiona filament at an oblique angle to the plane of the surrounding filament allows the so disposed with reference to the reflector that a preponderance of the. light rays emanating from the .said filament may be caused to encounter a desired section, for instance, the bottomor top of'the reflector.

0 This is ofcons'iderable advantage in connection with the prevention of glare. I have found that where the straight filament is disposed at an angle of 45 with the plane of the surrounding filament, the latter including or being parallel to the axis of the lamp, a conmetric center of the V.

Application filed August 17, 1921. Serial No. 492,887..

struction is provided which is particularly useful.

I prefer to use a V-shaped form for the surrounding filament which is preferably the major filament makingthe straight filament the minor filament. The minor filament is preferably'mounted in a plane which is sub stantially at right angles to the plane of the V-shaped major filament, the minor filament making an angle-of about 45 degrees with the line of intersection of the two planes. The mid-point of the minor filament substantially coincides with the geometric center of the majorfilament. As well as being practical and providinga mounting which is rigid and which eliminates sagging and interlocking filament troubles, this construction permits a concentrated distribution of light from the major filament and an effective distribution. from the minor. filament. The

common geometric center is preferably placed substantially in the focus of the usual parabolic reflector of, for instance, an automobile headlamp. The direction of the straight filament with reference to the 'top or bottom of the reflector will depend on the distribution desired. To cause more rays to strike the more efl'ective portion of the lower half of the reflector the straight filament should incline downwardly toward the frontof the reflector and to cause more rays to strike the more efiective portion of the upper half of the re flector the straight filament shouldlincline upwardly toward the front of the reflector.

In the accompanying drawing Fig. 1 is an elevation of an incandescent lamp embodying my invention; Fig. 2 is an elevation of the same at .right angles to the elevation of Fig. 1; Fig. 3 is an enlarged perspective view of the lamp filaments and supports therefor and 1s a diagrammatic vertical section of a re e ctor having mounted therein a lamp embodying my invention.

. The major filament 10 is V-shaped and is mounted upon the leading-in wires 11 and 12 which are carried by the stem 13 of the lamp 14. This filament is. of large diameter wire and. is closely coiled so. as concentrated source of light t'is mounted in the space surrounding the focus of the reflecting equipment with which it is used so that the said focus coincides with the geo- The minor filament This of small diameter filament wire and is coiled to concentrate a.-

to J[give a. fairly s I K considerable length of wire into a small space. i This filament has-a substantially uni-directional axis and is mounted upon the leadingin wire17 and upon the anchor 18 carried by the leading-in wire 12, so that it, makes an angle of substantially 45 degrees with the plane of the major filament 10. The geometric center of the minor filament 'substantially coincides at 19 with the geometric center of the major filament 10.

The parabolic reflector 20 in Fig. 4 has its focus atfll' which is also the location of the coincident geometric centers of the filaments.

1' As shown, the substantially uni-directional filament 15 is inclined downwardly toward the front of the reflector and a preponderance of light rays are-thrown against the rear of the lower half of the reflector 20;

Either filament or both may be lighted through the use of th usual controlling means for two-filament lamps. 1 When properly placed in the reflectingequipment each filamen't will be as much in focus as the other and will give the advantages common to two-fila-' ment lamps having both filaments in focus in addition to the specific advantages set forth in the preceding description.

Bothmajor and minor filaments are made of the proper length to obtain the desired distribution of light on the road or, in other words,'t he proper width of beam. While both of the geometric centers of-the filaments may be made to coincide with the focus of the refiector, it may be desirable to have either or both of such centers out of focus in order to obtain the desired light distribution. Any

such arrangementis to be considered to comp' within the scope of my invention as indlcated in the following claims.

What I claim as new and desire to secure by Letters'Patentof the United States, is y 1. An incandescent electric lamp comprising a bulb and twoindependent filaments of unequal candle power therein, one of said filaments being angular and having its axis sub-- stantially coincident with that of said bulb,

and the other fila'ment'being rectilinear and disposed obliquely to the plane of said angular filament with one portion thereof on one side and the other portion on the other side dimensions of the bulb and having their geometric centers substantially coinciding.

2. An incandescent electric lamp compris-.

ing a bulb and two independent filaments of unequal candle power therein, one of said filaments being angular and having its axis substantially coincident with that of said bulb,

ROBERT FALGE. a

of said plane, said filaments being confined within a space which is small compared to the 

